Sometimes the most lingering pain of a catastrophe comes from surviving the catastrophe.

“Sarah’s Key,” an often emotional new drama, looks at the horrors of the Holocaust. But instead of focusing on those who perished, it looks at Sarah, one little girl who lived. And then spent the rest of her life asking: Why?

It is a classic story of survivor’s guilt, and “Sarah’s Key” — based on the best-selling novel by the Anglo-French novelist Tatiana de Rosnay — often explores it with feeling.

The film details how many of the French needed little prompting to round up their neighbors and push them onto boxcars. It also shows the sudden, dangerous acts of kindness by those Christians who resisted, in often quiet but heroic ways.

Like last week’s “Snow Flower and the Secret Fan,” however, the old story is intercut with a modern one, as Julia, a middle-aged American journalist, uncovers the tip of a forgotten tale and begins to dig until she finally unearths the full truth.

Movie Review

Sarah’s Key (PG-13) Weinstein (102 min.) Directed by Gilles Paquet-Brenner. With Kristin Scott Thomas. In English and French, with English subtitles. Now playing in New York.Rating note: The film contains violence.Stephen Whitty's Review: TWO AND A HALF STARS

Although Kristen Scott Thomas gives a lovely and alert performance as the writer, this part of the story is at best a distraction, and at worst a kind of middlebrow magazine fiction. (De Rosnay has worked for Vanity Fair and Elle.)

We get a great many scenes detailing Julia’s marital problems, her fertility issues, her workplace discussions at her (barely believable) job and the difficulties she has dealing with all this ugly ancient history and watching it affect her modern life. But really, the point of Sarah’s story is not how it makes a rich journalist feel, more than half a century later. The point of Sarah’s story is Sarah.

Those scenes, with Sarah thinking, always thinking, of ways to protect her baby brother, to escape, to survive — have a real power, as we watch a civilized country slowly going to pieces.

And what follows — with an adult Sarah trying to make sense of her survival — has a terrible, windswept, desolate beauty.

It is curious. The “Snow Flower and the Secret Fan” movie would have been better if it hadn’t rewritten the book and added a modern framework. This movie of “Sarah’s Key” might have been better if it had rewritten the book, and simply focused on the past.

Because with great emotional tragedies like this one, we don’t need the doubly distancing, slightly literary effect of watching someone else watch the past come to life. We only need to see it ourselves. And shudder at how constantly present it feels.